The utilization of activated oxygen, or ozone, to clean, disinfect and deodorize is well known. Ozone is created when oxygen comes in contact with either ultraviolet light or electricity. The ultraviolet light or electricity breaks some of the oxygen molecules, each consisting of a pair of single oxygen atoms, into numerous single oxygen atoms. A portion of the single oxygen atoms then reassemble to form ozone (O.sub.3) molecules. The ozone molecules have very high oxidation capabilities, and thus, readily react with metals to form oxides, such as FeO.sub.2 and CrO.sub.2.
For many years, water treatment plants have positioned ozone generators in the waste water, or effluent, stream to introduce ozone into the effluent. The ozone kills bacteria and inactivates many viruses, fungi and other pathogens present in the effluent. More recently, producers of bottled water have incorporated ozone in the purification process to kill germs and bacteria that might be present in the water to be bottled. It is also well known to treat laundry with ozone. U.S. Pat. No. 5,097,556 issued Mar. 24, 1992, U.S. Pat. No. 5,181,399 issued Jan. 26, 1993 and U.S. Pat. No. 5,241,720 issued Sep. 7, 1993, all to Engle et al.; and U.S. Pat. No. 5,493,743 issued Feb. 27, 1996 to Schneider et al., each disclose methods and apparatus for utilizing ozone in the laundry wash process to treat laundry waste water.
The use of ozone in the laundry wash process produces a number of significant environmental benefits and cost savings. For example, when ozone is generated and introduced into the wash liquor during the wash cycle, the activated oxygen attacks the larger soil molecules and fragments them into smaller soil molecules that are more easily acted on by the components of the wash chemistry (e.g., detergents, bleaches, additives and surfactants). Thus, the wash chemistry is more effective in removing the soil from the laundry items. As a result, a greater percentage of the soil embedded in the laundry items dissolves into the wash liquor for extraction with the laundry waste water. In addition, the strong oxidizing capabilities of ozone act as a powerful disinfecting and cleansing additive for inactivating contaminants, such as viruses and other pathogens.
Because of the increased effectiveness of the wash chemistry and the oxidizing capabilities of the ozone, the concentration of the wash chemistry in the wash liquor can be substantially reduced. In some applications, the wash chemistry can even be eliminated entirely. Accordingly, less chemicals that are harmful to the environment are required to be used and subsequently discharged into the ground or municipal sewer system. The increased effectiveness of the wash chemistry shortens the wash cycle time of the laundry, thereby reducing the amount of energy used by the laundry. The number of rinse cycles and the average rinse cycle time can also be reduced because less chemicals must be extracted from the laundry items. Thus, the total amount of water needed to extract the soil and wash chemistry from the laundry is reduced. An added benefit of the reduced concentration of wash chemistry, wash and rinse cycle times and number of rinse cycles is that the useful life of the laundry items washed in an ozonated laundry system is increased.
With fewer chemicals present in the wash liquor, the waste water from the laundry process is less harmful to the environment, and is easier and less costly to treat. Sewage costs have risen dramatically in recent years in response to ever increasing water purification standards. The stricter municipal water purification standards require waste water, especially from commercial and industrial sources, to be thoroughly treated before the water is returned to the municipal water supply. In some instances, ozone can be utilized in a closed loop laundry machine to treat the laundry waste water after filtration. The filtered and ozone-treated water is then recycled back to the wash liquor for further use by the laundry machine. Accordingly, additional cost savings and environmental benefits are obtained.
For example, ozone has been applied to closed-loop laundry systems (FIG. 1a) which recycle the water after each cycle of the wash process. Water is supplied from a municipal water source to a storage tank 10 in a conventional manner. The water is used for the wash process and for refilling the storage tank 10 when the water level in the tank is low. Ozone generated by an ozone generator 12 is introduced into the water, for example, by pumps or injectors located in the storage tank 10. A laundry machine 14 is filled with the ozonated water at the start of the wash process. During a drain cycle of the wash process, the wash liquor is drained from the laundry machine 14 through filter 16 to collect particulate waste. One or more filters or filter screens can be used to progressively eliminate smaller particles without impeding the flow of the wash liquor. The filtered wash liquor is then returned to the storage tank 10, thereby creating a closed-loop laundry system. After the wash process has completed a final drain cycle, the treated waste water can be diverted to the sewer 18, or returned to the storage tank 10 for reuse.
Ozone has also been applied to open-loop laundry systems (FIG. 1b) which drain and divert the laundry waste water to a sewer 18 after each wash cycle and after each rinse cycle of the wash process. Water is supplied from a municipal water source to a storage tank 10 in a conventional manner. The water is used for the wash process and for refilling the storage tank 10 when the water level in the tank is low. Ozone generated by an ozone generator 12 is introduced into the water, for example, by pumps or injectors located in the storage tank 10. A laundry machine 14 is filled with the ozonated water at the start of the wash process. During a drain cycle of the wash process, the wash liquor is drained from the laundry machine 14 through filter 16 to collect particulate waste. At the end of each cycle of the wash process, the wash liquor is drained, filtered and diverted to the sewer 18 for further waste water treatment before rejoining the municipal water supply, thereby creating an open-loop laundry system.
Unfortunately, utilization of ozone in laundry systems typically produces off-gases because the concentration of ozone introduced into the laundry wash liquor is maintained at a constant level regardless of the size or content of the particular wash load. In commercial and institutional laundry facilities, various sizes of wash loads and various laundry items are washed. However, as previously mentioned, the concentration of ozone introduced into each wash process is maintained at a constant level. Once the ozone is introduced into the wash liquor in the laundry machine, agitation of the wash liquor causes the excess ozone to off-gas. Because the size and content of wash loads vary widely in commercial applications, different amounts of off-gasing are produced when a constant level of ozone is introduced into the wash liquor during the wash process.
As previously discussed, the concentration of the wash chemistry in the wash liquor can be reduced by the addition of ozone. However, current closed-loop and open-loop laundry systems and methods of cleaning laundry which utilize ozone do not adequately address the opportunity for further reduction of the wash chemistry, water and energy in response to wash loads that vary in size and content. Despite the benefits of using ozone in the laundry wash process, more efficient use of the wash chemistry and further reduction in energy and water consumption are possible. The additional benefits of using less wash chemistry and consuming less energy and water for washing and rinsing laundry are substantial, especially in commercial and institutional laundry facilities that wash large quantities of laundry.
It is also unfortunate that ozone molecules have a tendency to degenerate over time and revert to oxygen molecules and single oxygen atoms. Accordingly, it is preferable, whenever possible, to introduce ozone directly into the wash liquor in the laundry machine during the wash process to maximize the benefit provided by the ozone. A number of difficulties, however, are typically encountered when ozone is introduced directly into the wash liquor in the laundry machine. In particular, a secure, fluid-tight connection must be maintained between the injector utilized to introduce the ozone into the wash liquor and the laundry machine to prevent leakage of the untreated wash liquor into the ambient environment outside the laundry machine. At the same time, however, it is desirable that the injector be accessible and easily removed for cleaning, repair or replacement.
Accordingly, ozone injectors, and in particular elongate ozone diffuser stones or sparging rods, have previously been inserted through and welded to a wall adjacent the sump of the laundry machine. Oftentimes, access to the laundry machine with cumbersome welding equipment is limited. Further, once welded, the ozone injector is permanently fixed to the wall of the laundry machine and cannot be readily removed for cleaning, repair or replacement. Still further, welding often causes the metal in the area of the wall of the sump of the laundry machine to weaken, thus increasing the risk that the laundry machine will leak or rupture under the hydrostatic and hydrodynamic forces generated by the laundry machine during the wash process.
It is therefore apparent that a system and method for treating laundry with ozone is needed that varies the concentration of the ozone in the wash liquor in response to the wash load. Further needed is a system and method for treating laundry with ozone that varies the concentration of the ozone in the wash liquor in response to the size and content of the wash load. Further needed is a system and method for treating laundry with ozone that determines the minimum amount of wash chemistry required and the optimum amount of ozone to be introduced into the wash liquor for various wash loads, thereby reducing ozone off-gasing and further reducing the amount of energy and water consumed to wash and rinse the laundry items. Still further needed is a system and method for treating laundry with ozone that includes an adapter for removably securing an ozone injector adjacent the sump of the laundry machine.